


Let Them Eat Cake

by UnderElk (orphan_account)



Category: Undertale (Video Game)
Genre: Belly Kink, Eating Disorders, Ecto-Tongue (Undertale), Ecto-belly, F/M, Fat Shaming, Gender-Neutral Pronouns, Hurt/Comfort, Kink Shaming, M/M, Mild Smut, Slice of Life, Undertail, undertum - Freeform
Language: English
Status: Completed
Published: 2017-03-22
Updated: 2017-03-22
Packaged: 2018-10-09 02:29:25
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,318
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10401717
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/UnderElk
Summary: WARNING:  16+, Contains Undertale feederistic content (I.e- getting fat. I.e- liking it), also called ‘Undertum’. If this is not your thing, please keep scrolling. Thank you.Summary: Sans and (Reader) enjoying a relaxing evening of Movies and Chill, with a little tummy fun. ONESHOT. Read the tags, and it'll make sense.LAST WARNING, THIS IS BELLY FETISH TERRITORY!!! IF YOU DISLIKE, LEAVE!! Thank you again.





	

**Author's Note:**

> Rummaging through the good ole’ Undertum tag, and happened upon this adorable little post again: http://pinpuku.tumblr.com/tagged/stomach-mouth  
> Who else loves the idea of tummy mouth? I know I sure do (Well I like the idea of mouths on other body part other than the face lol)  
> So I was like, welp, I gotta write a fic about this now, no other way XD. Hope you enjoy regardless, and show PinPuku some L.O.V.E lol
> 
> P.s- Due to personal circumstances, I will be removing myself from the Undertum fandom permanently. However, I am leaving these stories for others to enjoy. I apologize to those wished for me to continue working on this story and others but I cannot. I apologize for the inconvenience and wish everyone the best.  
> -Elk

Sans sat propped up against a large amassing pile of pillows and rolled up blankets on his bed. His skull dipping down ever so slightly as he fought off sleep. This had been by far the worst Movies and Chill of all, with there being more ‘chill’ going on in the July heat outside than in Sans climate controlled bedroom. As soft snores broke over the faint whispers of the movie playing quietly on your laptop, you whipped your head over your shoulders to see Sans finally asleep with his chin tucked into his clothed rib cage. Your aggravation and endearment fighting each other as you struggled with the idea of waking him. He did work two jobs after all, and being topside made it more difficult on every working monster. Yeah ok, being trapped in the Earth DID suck, but having to work 8-12 hours on the daily was more than brutal.

Though the thought did temporarily take your mind off of Sans’s snoring, he was brought back to your focal point when a soft grumbling grew louder, indicating that he was hungry. Your stomach sounding off shortly after, you smirked at your synchronized thaumaturgy. You and Sans were getting pretty close (though you held no flame to Papyrus), but this magical synchronization was getting ridiculous.

Rolling over onto your bottom, you sat at the edge of the bed bending over to feel the floor for your fallen cellphone. It was misplaced during the make-out session earlier. Sure, the kissing and groping went no where but you couldn’t just let your chubby ‘bone’ buddy go hungry, could you? Plus, sitting up helped redefine the pit of hunger in your own gut, and hurried you along to the “GrubHub” app on your phone.

Pizza? No. Oooo, burgers…had that last week. Chinese? Sans always did the chopstick walrus thing, but you really didn’t feel like seeing that today. Tacos? Wrong AU…Pfft. Desserts? Looking at the selection area in the app, you reread the description again, to make sure you weren’t wrong. Delivery? For cakes? Since when?  
Since 2002, apparently. ‘Dolphin Delivers Desserts’ was the place (yeesh, what a name), and they’d been doing home a delivery since the early 2000′s. They were also relatively close by and still open. Hesitant, you looked back over to Sans who was still resting, you looked down at his tummy. A creeping thought popped into the back of your mind, as you jammed in your selection and went on to place your order.

It took less than 40 minutes, but soon there was a soft rap at the door, and you quickly went to answer it. Papyrus was always over Mettaton’s house these day so you knew there’d be no distractions for the entire evening. The young delivery boy was taken aback when you answered the door, shuffling nervously from foot to foot. You’d forgotten that the Fonts lived in a newly built town focused on monster/human integration, so his reaction was only natural since the bakery was located in a predominantly human neighborhood. Tipping him handsomely for sticking it out and remaining professional, you closed the door abruptly once he was gone, wondering if he was named Dolphin by chance. With the bag of goodies clutched to yourself and a gallon of milk pilfered from the fridge, you eagerly made your way back upstairs. 

Slumped down even further into the fluffy nest of bedding, Sans looked like a little old monster man, as he slept. He reminded you a bit of Gerson seated like that, however his tummy placed them worlds apart. It was protruding a fair bit from under his shirt now, the transparent blues beautifully showing his hipbones underneath a small muffin top. More of the ivory bones peaked up past his low riding grey sweatpants. Just that little bit of exposed ectoflesh and bone had your own stomach churning with flutters and pangs of hunger. Though, you were no longer interested in eating the food.

Drawing near the bed, you sat at the edge near his feet bones, pulling out the contents in the bag, loudly. The rustling caused Sans to stir awake, cracking one eye socket open at you. Your face broke into a one sided smile, as you greeted him softly, his eyes both opening as you handled the small Halloween themed three tier white chocolate cheesecake, a box of plain chocolate chip cookies, and a tub of butter pecan ice cream. The bottom of the plastic cake container was icy cold to the touch, chilling your hand in an instant, as Sans face heated up with a rich and vibrant shade of blue.

Now you had read somewhere online that cheesecake was the food of choice amongst humans who were into a subculture that praised overeating, along with a dairy concoction called heavy cream. Your ‘relationship’ with Sans hadn’t even involved food originally, but slowly over time it naturally became a big part of it. Neither of you had known why it happened, but after one of your many ‘chilling’ sessions, you started playfully feeding him popcorn while finishing a movie, absentmindedly rubbing his belly after. You didn’t even notice how wound up he was until he let out a shudder after you accidentally rubbed up against the tent in his shorts. Once starting off as a rare occasional thing, turned into the ‘IT’ thing for the both of you, meeting up to indulge in it and each other often. Admittedly the feeding turned mutual after a while, and you gained a bit yourself. Sans didn’t seem to mind it and you definitely didn’t mind that he was getting larger either. You even began incorporating the human cheesecake and heavy cream idea when you came over, this was a silent signal to let him know what you wanted when others were present. You both agreeing to save the desserts as the signature finish of the session.

Your ‘thing’ had lost all momentum when Mettaton and Papyrus started in on Sans about his weight one night at a party they were hosting. The two of them tag-teaming the both of you in front of a room full of snickering guests, riding him to diet and exercise, saying that he was becoming a ‘bad influence’ on you. Totally mortified by the intrusive and humiliating public shaming, the both of you just quietly resigned to the idea that maybe what you were doing was wrong. You knew Papyrus was coming from a place of love, but Mettaton…appearances meant everything to them now that they were on the surface, and they couldn’t just lower themselves to hang out with a couple of fatty losers… Even though Sans retook control of the situation with some quickly fired puns and self deprecating jokes, the damage was already done.

This significantly reduced what you and Sans had ‘accomplished’. To say that you were disappointed was an understatement, as you’d been secretly proud of how big you’d gotten him. Though you’d never admit it out loud to anyone since you were definitely sure humans and monsters were against this type of lifestyle. You both remained silent about what happened that night, opting to play it off, but stopping the feeding sessions indefinitely. It had been months since he or you had even brought it up, the sex had died down to the non-existent state currently present tonight. 

The blue on his face was accompanied with lighter blue sweat droplets, as they rolled down his rounded face. His eyelights flickered every which way but towards you, thumbing his fingers together as his smile held onto the embarrassed strain that pulled on its corners. He tried protesting but the sound died away in his non existent throat. You held your air of confidence, but admittedly it was beginning to falter as the silence swelled with tension. Maybe this was a mistake. Maybe he really didn’t want this anymore…or maybe he just didn’t want you… I mean you’d hadn’t been together in a while, and he had lost most of his weight while you still struggled with yours…

Shaking off the notion, and remembering how much you’d paid for just the mini ‘Halloween’ themed cake alone. You placed every unopened container on the bed, reaching beside you to bring up the plastic milk carton from off the floor. The dairy vessel was also cold, so you placed it in between Sans legs, at the base of his femurs. This forced his legs apart and to look at you. You weren’t about to waste this powerplay and possible window of opportunity.  
The milk sat innocently between the two of you, but your intentions weren’t, heating up your face as well. You wanted back what you had once before, but were uncertain of were he stood. Instead of talking about your concerns and desires, you just moved your hand back to the cake and popped the container open. The weird human seal made it hard to peel the container open without A. destroying the contents inside, or B. dumping the entire dessert on the bed. Why did humans have to complicate everything?! However frustrated, you managed it just as Sans stomach gave off a quick gurgle of approval. A visible quiver running through his belly like a faint tremor.

You had asked for plastic utensils along with the desserts, two to be exact and shook the bag until they popped out. Peeling the plastic back, you watched Sans for his reactions. His sight first lay upon your hands, gaze flushing as it slowly scanned up to your equally watching eyes, and then shooting over quickly to the wall his bed rested up against. You placed your hand on his stomach, rubbing it slowly while looking into his face, cake now speared with the fork and in your lap. He wouldn’t look at you.

The blue hue grew darker, as you shifted closer to him, careful to keep the cake balanced. The decorative dessert smelled wonderful, it’s cold crisp form unable to mask the waft of chocolate and honey like smell that drifted up. The brown and cream swirls of it’s body where complimented by the drizzled dark chocolate sauce and sea salt caramel milk chocolate shavings that was present on every layer. The tops and sides were adorned with cute little orange dyed pumpkins, green witch heads in black hats and purple bats, all made out of some sort of edible molded whipping cream. The sweet toppings pairing perfectly with the decadent savoriness of the cream cheese based cake. Each tier thick and smaller than the last. 

Now pressed up to Sans hipbone, you turn your entire body to face him, hand still hard pressed into his gut. Sitting criss-cross apple sauce, you were close enough to his turned away face, that you decided to whisper into his ear hole, rubbing his belly in little circles that traveled up and down the soft organ.  
Taking a forkful out the middle layer, you bring a small bit of caramel and chocolate shavings up as well, taking to switch hands so now your outside hand is rubbing Sans belly and the inside one is offering him the cake.

“I-I don’t know about this”. The timidness of his voice mildly catches you off guard. His face now turned to you, he gives your hand a weak push, to remove it off of his belly, trying to shift himself further towards the wall. You press into him harder, your smile curling a bit as you float the cake up to his teeth. Your not sure how to convince him, but then you think back to the first time you’d ever used cheesecake in a session and try something.

Looking him in the eye you tell him how much you know he wants this, that you know how much he wants to be fed by you, to be touched by you, how much he likes it when you touch him this way. You proceed to squeeze the soft chub on his side with your hand, the flesh swelling in between your fingertips. His breathing hitches at your words, but you keep eye contact as you float the forkful of cake right up to his slotted mouth.

His hesitation and pain of embarrassment are still there, with is desires and uncertainty locked in struggle behind his gaze. That look burns you up but also softens your approach. He needs this, you need this, Stars you both really really want this but you know he needs a bit more motivation. Bringing your hand around to his back, you raked your hand across a love handle that’s underneath his ribs, going back to where his ear would be has he breathes out a puff of air. Your tone holds desperation as you whisper for him that he’s not alone and that your in this together and you won’t abandon him. That you don’t care what people think and want him just the way he is, needing not change for anyone. You continue to rub and squeeze his body with vigor, imploring him to eat for you while your free hand continues to explore over his sides and palm the underside of his belly. Your whispering voice is broken and needy as you beg him to let you do this for him, stuff him until he is too full to move and pleasure him after. You promised him how good you’d make him feel, and how long you’ve wanted this, how badly you wanted him in this way, all the while running your own soothing magic into him, heat pooling in your lower abdomen.

His groans make your stomach physically contract, as curls of pleasure burned through your tummy, winding up your back as the heat races along your spine. His mouth opens to receive the first forkful.

The third bite produces the best needy sounds you’d ever managed to pull out of Sans, his belly jiggling as you feed him more cake. You rake your fingertips all over his torso, starting by ghosting over his ribs and running your fingers in between the gaps of the bones. As you spread your hand over the front of his chest, you began strumming down, feeling Sans tense and seize as you lingered in the slots he really likes. Head thrown back into the pillows, you stuffed the next bite into his mouth.  
Suddenly he grabs your wrist and lightly pushes you away. Sweating and fork still in mouth, Sans asks you to hold up while clutching his belly. Confused and a little concerned, he breathes out “I really wanna try somethin’ but I really don’t wanna freak you out.”

Intrigued and impatient, you nod curtly and assure him your not going anywhere. Looking at you he stares a moment too long, were you respond by urging him to go ahead with the show and tell.

It takes you a moment to realize, but the crackling sound of blue magic makes a whole lot of sense when a crease is formed from out of the pucker of his belly button. However that sense flies right out the window when the line quivers and appears to wiggle, as it tears away to reveal a row of long spiked teeth curving down into a smile. Stunned and sorta shocked, Sans pipes up.

He explains that it was something he saw in a weird episode of an anime Alphys and Undyne watched, but instead of on the belly the character wielded duel mouths, one on both hands. He always wanted to try it, but after what happened… he was unsure if he’d ever get the chance to. Searching your face he quickly adds “Heh, might not have been one of my best ideas…”

He’s sweating a lot more now, as the mouth of the tummy…the mouth ON the tum-the tummy mouth?! Uhhgg…You have no valid name for what the monster in front of you has created, however, the first thing you do is ditch the fork.

With both his hands resting on the sides of the magical grinning gut Sans nervously looks at you, losing confidence in himself fast. Knowing him he’s introspectively beating himself up, thinking he’s scared you off. With a sigh, you shake your head piercing his wavering gaze with a arrogant smirk. How many times do you have to convince this bonehead your open to anything, as long as its with him?

Catching him off guard, you slide the entire cake into the awaiting jaws of the beast, which surprisingly it takes in stride, abet struggling to chew everything. Fascinated by the mechanics of this magic, you clasp your hand on it’s chewing mouth and run your fingertips across the line of it’s lips???

The stomach doesn’t react to you, but Sans melts out of the paralysis that he somehow contracted once the cake was being devoured, squirming under the mynute ministrations of your fingertips, bucking up.. His face begins turning deep violet, a color you’ve never seen before and your almost convinced he’s hurt until he lets out a poorly controlled whine. Quickly dropping the empty container on the bed, you voraciously scrape your fingers in multiple directions across Sans gut as he chokes on his own breath with a long ‘hnnnngh’. He quickly covers his mouth, trying to stifle the muffled noises pouring out of him. The mouth on the tummy, finished chewing reopens and wraps your left hand up in its tongue, slobbering all over it as your pulled into it’s awaiting mouth. It sucks over every digit, teeth grazing over your wrist pleasurably, appendage cold from the cake. So you run your hand across the roof of the makeshift mouth, and over Sans bottom floating ribs watching as he arches up with a loud ‘Ahhh, ahhh HAH.’

You freeze, and the mouth spits your hand out as Sans writhes. Expecting saliva, the moment your hand is out it’s covered in a thick goo with the smell of pure magic and cheesecake. The pure magic holds lifted notes of Sans chalky bones, ketchup and the sweet glaze of echo nectar from echoflower brewed whiskey. He had gone drinking without you?! How could he! The combination held a spicy smell with a sweet organic base masked in a soft chocolate cream. Tempted to taste it, the mouth quickly nips your hand back into its chasm, tongue urging you to feel around again, so you do.

The look on Sans face, takes you aback, as his eyesockets are screwed shut, bone brow furrowed, pinched together in ecstasy, face still violet and panting hard. His face is so broken right now, you feel your loins burning with need, moving your hand around inside his tummy to play with his spine. Cocking your head to the side, you watch his face and listen to his sobbing as you slowly but firmly jerk up and down his spine, gripping his lumbar hard. As you open the box of cookies with your other free hand you drink in his reactions. Eye sockets only slits, Sans watches and whimpers as you take a handful of four cookies from the chocolate chip double dozen you ordered. “N-no wait, I need a minute” is all but a whisper over the happy gurgle of the tummy monster eyeing the dessert…with…no eyes???

You giggle, and ask the tummy directly if it wants the treats, and if it’s a good boy. Unexpectedly Sans belly answers with a burp, opening it’s maw with your hand inside. Removing your hand, you toss the cookies in, and then dump the entire box along with them. Sans arches off the bed, and he looks almost pained. Your worried you’ve hurt him again, until you notice his erection straining in his pants. Your smirk returns, watching as his tummy begins filling out nicely…


End file.
